1. Field of the Invention
The invention relates to a composite lens structure, and in particular to a composite lens structure capable of focusing and diffusing light.
2. Description of the Related Art
Light emitting diodes, rather than CCFLs, are applied in backlight modules due to low cost and more simplified structure. A backlight module comprises optical films with various functional components, such as a light guide plate, a diffusion plate, a brightness enhancement film, and a dual brightness enhancement film. A composite optical film has two or more described functions, for example an optical structure is formed on a light guide plate to have light guide and light diffusion functions, or an optical structure is formed on a diffusion plate to have light diffusion and brightness enhancement functions. The brightness enhancement structure is a rhombus lens or the like, which is disclosed in U.S. Pat. No. 5,300,263. An optical structure with two micro structures alternatively arranged has the composite optical functions, which is disclosed in U.S. Pat. No. 5,177,637 or U.S. Pat. No. 5,861,990.